Cyclone furnaces



May 29, 1956 H. SEIDL CYCLONE FURNACES Filed July 7, 1952 FlG.1

ATTORNEY I INVENTOR J /erbert 562d] v.0. II

limited States Patent 6 CYCLONE FURNACES Herbert Seidl, Oberhausen,Germany, assignor to The Babcock & Wilcox Company, New York, N. Y., acorporation of New Jersey Application July 7, 1952, Serial No. 297,424

Claims priority, application Germany July 12, 1951 8 Claims. (Cl.110-28) The present invention relates in general to a method of andapparatus for burning ash-containing solid fuels which are characterizedby a high output of high temperature gaseous products of combustionwhich are substantially free of entrained slag or ash particles.

In practicing the invention, the combustion constituents are introducedinto a combustion chamber of the cyclone type, generally similar to thecyclones dislosed, for example, in the U. S. patent of Bailey 2,357,301,issued September 5, 1944, and the high temperature combustion productsdeveloped therein are introduced into a succeeding combustion chamber ofa similar type, wherein the combustion is substantially completed and aseparation of the gaseous products and molten slag particles issubstantially effected.

In accordance with the invention, a granular ash-containing solid fuel,in a high velocity stream of superatmospheric pressure carrier air, orother suitable gaseous medium, is directed tangentially into a fluidcooled cyclone chamber adjacent one end thereof and caused to follow ahelical path of travel longitudinally therein, with secondary combustionair in regnlable quantity also being admitted tangentially, from whencethe products of combustion are discharged tangentially from a pointadjacent the opposite end into a second similar fluid cooled cyclonechamber which in accordance with the present invention is arranged withits longitudinal axis at right angles to the axis of the first chamber.

More particularly, the invention involves one or more primary cyclonetype combustion chambers positioned with horizontally extending axes,having a tangential fuel and air inlet at or adjacent one end thereofand a tangential outlet for gaseous products of combustion and a slag ator adjacent their opposite end portion arranged to dischargetangentially into an upright cyclone chamber at a position intermediatea top outlet therein for gaseous products of combustion and a bottomoutlet for separated molten slag.

The invention relates more particularly to a cyclone furnace unitconsisting of one or more water cooled refractory cylindrical primarycyclone combustion chambers with helical flame guidance and the drainingof molten slag into a secondary cyclone combustion chamber, followed bya radiant heat absorption chamber, the volume of the secondarycombustion chamber being smaller than the sum of the volumes of theprimary combustion chambers.

In the cyclone furnace unit of the invention, the major portion of theslag is separated in the primary cyclone chamber, most of the remainingslag is separated in the secondary chamber and a small portion passesthrough the steam generator to the stack. The primary and secondarycyclone combustion chambers are relatively arranged and interconnectedin such a way that slag is discharged from the unit at only one point.

However, the solution of the several problems interfere with each other.For example, the seondary combustion chamber has as its aim to burn outthe flame or complete 2,747,526 Patented May 29, 1956 ice thecombustion, to separate the liquid slag contained in the products ofcombustion, to maintain the slag sufficiently hot for it to drainwithout disturbance, and to do all this at the lowest permissiblepartial load.

On the other hand it is also the function of the secondary combustionchamber to cool the furnace gases discharged through tubes of a slagscreen so they are re duced below the melting temperature of the slagand thereby give no rise to slag depositions in the subsequent radiantheat absorption chamber and connected convection heating surfaces.

In prior cyclone furnace units the volume of the secondary combustionchamber is usually a multiple of the volume of the cyclone combustionchamber and hence at partial load there is a high degree of cooling ofthe furnace gases so that the permissible partial load is necessarilyset high. The two aforementioned problems are best solved when the slagoutlet of the secondary combustion chamber is positioned at its hottestpoint, i. e. in the vicinity of the furnace gas inlet from the primarycyclone chamber, while the slag removal screen is substantially removedtherefrom.

The present invention associates one or more primary cyclone combustionchambers with one or more secondary combustion chambers of a cyclonetype in a manner to insure completion of combustion, maintenance of slagfluidity for discharge and high degree of slag removal from thedischarged high temperature heating gases.

The various features of novelty which characterize this invention arepointed out with particularity in the claims annexed to and forming apart of this specification. For a better understanding of the invention,its operating advantages and specific objects attained by its use,reference should be had to the accompanying drawings and descriptivematter in which a selected embodiment of the invention has beenillustrated and described.

Of the drawings:

Fig. 1 is a transverse sectional elevation through the main axis of amulti-cyclone chamber furnace constructed in accordance with theinvention, as indicated by line 1-1 in Fig. 2; and

Fig. 2 is a sectional plan view of the multi-cyclone chamber furnace,taken in a plane perpendicular to the plane of Fig. l, as indicated byline 22 in Fig. 1.

As shown in the. drawings, a vertically elongated cylindrical secondarycombustion chamber 2, which has walls with cooling tubes 28 providedwith a refractory composition 21 on the inner or fire side and an outerinsulating jacket and metal shell 22 is arranged coaxially below aradiant chamber 1. Chamber 1 is designed similar to the combustionchamber of a radiant steam generator having its walls lined with coolingtubes 23 connected to the fluid circulation of the generator. The gasdischarge opening 3 connecting the upper end of chamber 2 and theradiant chamber is of octagonal configuration conforming to theoctagonal arrangement of the Wall of the radiant chamber 1. However theopening 3 may have a circular or other form symmetrical to the verticalaxis of chamber 2.

Two horizontally elongated cylindrical primary cyclone chambers 6 and 7are positioned laterally and at opposite sides of the chamber 2, withtheir axes extending horizontally. These cyclone chambers have disc typeclosures at both ends, and tangentially arranged outwardly extendingoutlet passages 14} and 11 respectively connected to the secondarychamber 2. The cylindrical and end walls of the primary chambers areprovided with cooling tubes which are connected into the circulation ofthe vapor generator.

A fuel-primary air mixture is supplied tangentially to the two cycloneprimary combustion chambers 6 and 7 adjacent one end through respectivefeed conduits 8 and 9 from suitable sources of prepared fuel and airunder superatmospheric pressure. The secondary combustion air issupplied as required by longitudinally extending nozzles 14 and 15,being likewise introduced tangentially with the same direction ofrotation as the corresponding primary airand fuel. The resulting flameand products of combustion move in a helical path along the cylindricalwall of the cyclones and develops a temperature above the fuel ashfusion temperature so that the ash of the fuel melts to a slag.outwardly through passages 10 and Ill entering tangentially into thesecondary combustion chamber 2 over the inwardly sloping bottom 24. Therelative arrangement of the passages 15 and 11 is such as to cause thesame direction of rotation of the gases and suspended slag particlestherefrom in the secondary chamber 2. Slag flowing along the bottom ofpassages 10 and 11 can pass directly to the outlet 4. The flame andproducts of combustion move upward along the walls of the cylindricalsecondary combustion chamber in helical paths. suspension are separatedby centrifugal force and deposited on the chamber walls. The refractoryfaced wall with its coating of slag is maintained at a temperature whichis above the melting point of the slag by the residual combustiontherein. The molten slag particles on the vertical walls draindownwardly by gravity to flow in molten form over the downwardly slopingfloor 24 to slag outlet 4. The inclined bottom of the secondary chamberincludes water cooling tubes and refractory facing thereon, the tubesbeing extensions of the tubes 20 about the cylindrical portion ofchamber 2. These tubes are connected into the circulation of thegenerator.

In order that the helical path of the gases will continue into theradiant chamber 1, the customary slag screen 6 and 7 will operate atsubstantially superatmospheric pressure in order that the gaseousproducts of combustion will enter the secondary chamber 2 throughpassages 19 and 11 at substantial velocities, chamber 2 may operate at apressure substantially different from that of the atmosphere.Accordingly a water sealed slag granulating and discharge device 5 ispositioned beneath the slag opening 4.

T he internal volume of the cylindrical secondary combustion chamber 2is less than the combined volumes of the primary cyclone chambers 6 and7. While the seccndary cyclone chamber may be cooled below the meltingpoint of the slag during a partial load or fuel burning rate when onecyclone chamber is taken out of service, the lower portion thereof willremain at a high temperature, which is important for the undisturbeddischarge of s1 because of the discharge of hot gases from the operatingprimary cyclone chamber into the lower portion of the secondary chamberin proximity to the slag outlet 4.

l t is therefore practical to lower the permissible partial load to theextent that it is still possible to keep the slag on the bottom of thesecondary cyclone chamber 2 fluid. Conditions will be more favorable,the smaller the volume of the secondary combustion chamber 2 and thegreater its length in relation to its diameter. It is preferable if eachprimary cyclone chamber has a separate secondary combustion chambercoordinated with it, when considered solely from the partial loadstandpoint. However it is more desirable as regards the arrangement ofthe The slag flows with the furnace gases 1 Slag particles in ash orslag disposal equipment if the slag is discharged from only one point inthe installation, and it will therefore be preferable to coordinateseveral primary cyclone combustion chambers with one secondarycombustion chamber.

While in accordance with the provisions of the statutes 1 haveillustrated and described herein the best form and rode of operation ofthe invention now known to me, those skilled in the art will understandthat changes may be made in the form of the apparatus disclosed Withoutdeparting from the spirit of the invention covered by my claims, andthat certain features of my invention may sometimes be used to advantagewithout a corresponding use of other features.

I claim:

1. A cyclone furnace unit for burning ash-containing solid fuel whichcomprises a primary cyclone chamber of substantially circularcross-section arranged with its longitudinal axis substantiallyhorizontal, means for in troducing a stream of air and ash-containingfuel in suspension into said chamber and effecting a helical path oftravel thereof along the circumferential wall of said chamber, saidprimary chamber having an outlet passage for products of combustionopening therefrom in tangential relation to said wall, a secondarycyclone chamber of substantially circular cross-section arranged withits longitucinal axis substantially vertical and having an inlet passageforming a continuation of said outlet passage and arranged tangentiallyof said secondary chamber for developing a helical gas flow stream alongthe circumferential wallof said secondary chamber, a slag dischargeopening from the lower portion of said secondary chamber, and a gasoutlet formed at the upper end of said secondary chamber.

2. A cyclone furnace unit as defined in claim 1 wherein said inletpassage is positioned closely adjacent the lower end of said secondarychamber adjacent said slag discharge opening.

3. A cyclone furnace unit as defined in claim 1 wherein the lower end ofsaid secondary chamber has a water tube cooled bottom through which saidslag opening extends, and said inlet passage is positioned closelyadjacent said bottom.

4. A cyclone furnace unit as defined in claim I wherein the gas outletopening from the upper end of the secondary chamber is of lessertransverse dimension than the diameter of the secondary chamber and hasa depending lip associated with its margin.

5. A cyclone furnace unit as defined in claim 1 wherein the gas outletfrom the upper end of the. secondary chamher is connected to the lowerend of an elongated upwardly extended fluid cooled radiant heatabsorbing chamber of a vapor generator.

6. A cyclone furnace unit for burning ash-containing solid fuel whichcomprises a plurality of primary cyclone chambers of substantiallycircular cross-section arranged with its longitudinal axis substantiallyhoriozntal, means for introducing a stream of air and ash-containingfuel in suspension into each of said chambers and effecting a helicalpath of travel thereof along the circumferential walls of said chambers,said primary chambers having outlet passages for products of combustionopening there from in tangential relation to their walls, a secondarycyclone chamber of substantially circular crosssection arranged withlongitudinal axis substantially vertical and having a plurality of inletpassages forming continuations of corresponding outlet passages andarranged tangentially of circumferentially spaced portions of saidsecondary chamber, a slag discharge opening from the lower portion ofsaid secondary chamber, a gas outlet from the end of the secondarychamber opposite the slag outlet, said inlet passages being positionedcloser to the slag discharge opening than to the gas outlet.

7. A cyclone furnace unit as defined in claim 6 wherein References Citedin the file of this patent the volume of the secondary cyclone chamberis less than UNITED STATES PATENTS i f volumes of t p y cy n rs- 2357303Kerr et aL Sept. 5, 1944 cyc one furnace unit as defined in claim 6wherein 5 2,395,103 Clausen et a1 Feb. 19 1946 the axial length of thevertically extending secondary cyclone chamber is greater than the axiallengths of the FOREIGN PATENTS horizontally extending primary cyclonechambers. 925,264 France Mar. 24, 1947

1. A CYCLONE FURNACE UNIT FOR BURNING ASH-CONTAINING SOLID FUEL WHICHCOMPRISES A PRIMARY CYCLONE CHAMBER OF SUBSTANTIALLY CIRCULARCROSS-SECTION ARRANGED WITH ITS LONGITUDINAL AXIS SUBSTANTIALLYHORIZONTAL, MEANS FOR INTRODUCING A STREAM OF AIR AND ASH-CONTAININGFUEL IN SUSPENSION INTO SAID CHAMBER AND EFFECTING A HELICAL PATH OFTRAVEL THEREOF ALONG THE CIRCUMFERENTIAL WALL OF SAID CHAMBER, SAIDPRIMARY CHAMBER HAVING AN OUTLET PASSAGE FOR PRODUCTS OF COMBUSTIONOPENING THEREFROM IN TANGENTIAL RELATION TO SAID WALL, A SECONDARYCYCLONE CHAMBER OF SUBSTANTIALLY CIRCULAR CROSS-SECTION ARRANGED WITHITS LONGITUDINAL AXIS SUBSTANTIALLY VERTICAL AND HAVING AN INLET PASSAGEFORMING A CONTINUATION OF SAID OUTLET PASSAGE AND ARRANGED TANGENTIALLYOF SAID SECONDARY CHAMBER FOR DEVELOPING A HELICAL GAS FLOW STREAM ALONGTHE CIRCUMFERENTIAL WALL OF SAID SECONDARY CHAMBER, A SLAG DISCHARGEOPENING FROM THE LOWER PORTION OF SAID SECONDARY CHAMBER, AND GAS OUTLETFORMED AT THE UPPER END OF SAID SECONDARY CHAMBER.